TRI-STATE SIGNAL TRANSMISSION METHOD AND ITS TRANSMITTER-RECEIVER THROUGH BALANCED LINE

PURPOSE:To realize the transmission whose band width is saved more than that for binary signal transmission. CONSTITUTION:The system is provided with a transmitter 3, a receiver 4, a balanced line comprising two electric wires X, Y interconnecting the transmitter 3 and the receiver 4, and the transmitter 3 sets a potential sent to the 1st electric wire X to be high and a potential sent to the 2nd electric wire Y to be low when a signal to be sent is logical 0 and sets a potential sent to the 1st electric wire X to be low and a potential sent to the 2nd electric wire Y to be high when a signal to be sent is logical 1 to send the signal to the receiver 4. In the signal transmission method using the balanced line for signal transmission as above, a tri-state signal having logic levels 0, 1, 2 is adopted for the signal sent by the transmitter 3 and the signals with logic levels 1, 2 are the same as above and the signal with logical 2 is sent to the receiver 4 by increasing the impedance between the 1st electric wire X and the 2nd electric wire Y.